The basic goal of the research is to elucidate the details of the complex redox chemistry of biologically important pteridines in terms of the electrical potentials required for the electron-transfer processes to occur, the nature and properties of intermediates formed and the course and controlling factors for their follow-up chemical and/or electrochemical reactions. In addition the products formed in the redox reactions of these pteridines are sought. The ultimate objective of these investigations is to provide a solid foundation to understand the role of pterin cofactors in enzymic reactions. A major effort during the current year was aimed at chemical synthesis of a number of methylated tetrahydropterins. The following compounds have synthesized: 2-imino-3,6,7,8-tetramethylpterin, 2-imino-3,8-dimethylpterin, 2-dimethylamino-6, 7-dimethylpterin, 2-dimethylamino-4-methoxy-6, 7-dimethylpteridine, 2-dimethylamino-6, 7,8-trimethylpterin and their corresponding tetrahydrocompounds.